Capacitor for interposers and methods of manufacture thereof

ABSTRACT

Capacitor designs for substrates, such as interposers, and methods of manufacture thereof are disclosed. A through via is formed in the interposer, and a capacitor is formed between a lower level metallization layer and a higher level metallization layer. The capacitor may be, for example, a planar capacitor with dual capacitor dielectric layers.

BACKGROUND

Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment, as examples. The semiconductor industry continues to improve the integration density of various electronic components (e.g., transistors, diodes, resistors, capacitors, etc.) by continual reductions in minimum feature size, which allow more components to be integrated into a given area. These smaller electronic components also require smaller packages that utilize less area than packages of the past, in some applications. One type of smaller packaging that has been developed is three-dimensional (3D) ICs, in which two die or ICs are bonded together and electrical connections are formed between the die and contact pads on an interposer.

In these situations, power and signal lines may be passed through the interposer, from connections on one side of the interposer to dies or other electrical connections on an opposing side of the interposer. The interposer may also include passive components, such as a decoupling capacitor. The current from a power supply flows through the power lines, logic gates, and finally to ground. During the switching of the logic gates, a large amount of change in the current may occur within a short period of time. Decoupling capacitors are used to absorb these glitches during current switching. Decoupling capacitors function as charge reservoirs by maintaining a constant voltage between the supply voltage and ground, preventing momentary drops in the supplied voltage.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIGS. 1-7 are cross-sectional views of various intermediate stages of forming a device in accordance with an embodiment.

Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the embodiments of the present disclosure are discussed in detail below. It should be appreciated, however, that the present disclosure provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the disclosure, and do not limit the scope of the disclosure.

Embodiments of the present disclosure are related to packages for semiconductor devices that utilize an interposer as a component, such as 3DICs. Methods of forming interposers having capacitors formed thereon, such as metal-insulator-metal (MIM) capacitors (e.g., decoupling capacitors), will be described herein.

Referring first to FIG. 1, there is shown a cross-sectional view of a substrate 10 in accordance with an embodiment. The substrate 10 may be any suitable substrate, such as a silicon substrate, a 1/2/1 laminate substrate, a 4-layer laminate substrate, a ceramic substrate, or the like. While the embodiments discussed herein are described in the specific context of an interposer to be used to mount one or more integrated circuits thereto, other embodiments may utilize aspects of the present disclosure in other situations.

One or more openings, such as opening 12, are formed in the substrate 10. As will be discussed in greater detail below, the opening 12 will be subsequently filled with a conductive material to form through vias (TVs). As illustrated in FIG. 1, in an embodiment the opening 12 extends partially into the substrate 10. Subsequent processing may be performed to thin the backside of the substrate 10 to expose and form electrical connections to the TVs.

The opening 12 may be formed by, for example, etching, milling, laser techniques, a combination thereof, and/or the like recesses from a top surface 10 a of the substrate 10. For example, in an embodiment, photolithography techniques may be used. Generally, photolithography involves depositing a photoresist material, which is then masked, exposed, and developed, thereby leaving the section of the substrate 10 that is to become the opening 12 exposed. After the photoresist material is patterned, an etching process may be performed to form the opening 12 in the substrate 10 as illustrated in FIG. 1. In an embodiment in which the substrate 10 includes a silicon interposer, the etching process may be a wet or dry, anisotropic or isotropic, etch process. After the opening 12 is formed, the photoresist material may be removed using, for example, an ashing process.

After the opening 12 is formed, a liner 14 may be deposited over the surface of the substrate 10, such as by chemical vapor deposition (CVD), atomic layer deposition (ALD), physical vapor deposition (PVD), thermal oxidation, a combination thereof, and/or the like. The liner may include an oxide, such as SiO₂, a nitride, such as Si₃N₄, SiC, SiON, or TiN, or other dielectric materials.

The opening 12 is filled with a conductive material, thereby forming TV 16 in accordance with an embodiment. The TV 16 may be formed, for example, by depositing a layer of the conductive material over the liner 14 and within the opening 12. The conductive material may be formed by an electro-chemical plating process, CVD, ALD, PVD, a combination thereof, and/or the like. Examples of conductive materials include copper, tungsten, aluminum, silver, gold, a combination thereof, and/or the like. Excess conductive material may be removed by, for example, a planarization process, such as a chemical mechanical polishing (CMP) process, using the liner 14 as a stop layer, thereby forming the TV 16 as illustrated in FIG. 1.

Referring now to FIG. 2, there is shown a first etch stop layer 18 and a first insulating layer 20 formed over the substrate 10 in accordance with an embodiment. The first etch stop layer 18and the first insulating layer 20 act as a dielectric layer in which metallization layers may be subsequently formed. The first etch stop layer 18 provides an etch stop during later processing, such as forming electrical connections to the TV 16. In an embodiment, the first etch stop layer 18 may be formed of a dielectric material such as a silicon-containing material, a nitrogen-containing material, an oxygen-containing material, a carbon-containing material or the like. The first insulating layer 20 may include a dielectric or low-k dielectric layer. For example, in an embodiment the first insulating layer 20 is formed of SiO₂, borophosphosilicate glass (BPSG), tetraethylorthosilicate (TEOS), high density plasma (HDP) oxide, spin on glass (SOG), undoped silica glass (USG), fluorinated silica glass (FSG), BLACK DIAMOND™ (Applied Materials of Santa Clara, Calif.), or other insulating materials.

FIG. 2 also illustrates formation of a first metallization (M1) layer 22 interconnecting the TV 16 and/or components formed on the substrate 10 in accordance with an embodiment. In some embodiments, the first metallization layer 22 may provide an electrical connection to the capacitor formed in subsequent processes. Openings corresponding to the first metallization layer 22 may be formed in the first insulating layer 20 and the first etch stop layer 18 using for example, a damascene process. Conductive material is deposited over the first insulating layer 20 and the first etch stop layer 18 to fill the openings. Excess conductive material may be removed using one or more etch processes or CMP processes, leaving the structure shown in FIG. 2. In an embodiment, the conductive material used to form the first metallization layer 22 may include, for example, aluminum, copper, tungsten, combinations thereof, or the like. A barrier and/or liner (not shown) may also be formed in the opening prior to the formation of the first metallization layer 22.

FIG. 3 illustrates forming a second etch stop layer 24 and material layers over the first metallization layer 22 and the first insulating layer 20, and the material layers are to be subsequently patterned to become MIM capacitors, e.g., electrode layers 26 and capacitor dielectric material layers 28, in accordance with an embodiment. In an embodiment, the electrode layers 26 include a first electrode layer 26 a, a second electrode layer 26 b and a third electrode layer 26 c, and the capacitor dielectric layers 28 include a first capacitor dielectric layer 281 and a second capacitor dielectric layer 2811. In an embodiment, the first capacitor dielectric layer 28I is formed between the layers 26 a and 26 b, and the second capacitor dielectric layer 28II is formed between the layers 26 b and 26 c. The electrode layers 26 may include a layer of conductive material such as TaN, TiN, or the like, for example, although other materials may be used. The capacitor dielectric material layers 28 may include a high dielectric constant (k) material having a dielectric constant greater than the dielectric constant of SiO₂, for example, such as ZrO, HfO, Si₃N₄, or barium strontium titanate (BST), although other materials may be used.

The second etch stop layer 24 provides an etch stop during later processing, such as forming MIM capacitors, as well as providing an additional isolation layer between the subsequently formed capacitor and the first metallization layer 22. In an embodiment, the second etch stop layer 24 may be formed of a dielectric material such as a silicon-containing material, a nitrogen-containing material, an oxygen-containing material, a carbon-containing material or the like. The first etch stop layer 18 and the second etch stop layer 24 may be formed of a same type of material or a different type of material.

Next, referring to FIG. 4, the third electrode layer 26 c and the second capacitor dielectric layer 28II are etched through one or more photolithography processes as a first pattern. Then, the second electrode layer 26 b and the first capacitor dielectric layer 28I are etched through one or more photolithography processes as a second pattern, as shown in FIG. 5. Thereafter, as shown in FIG. 6, the first electrode layer 26 a is etched through one or more photolithography processes as a third pattern. The patterned layers 26 a, 28I and 26 b forms a first capacitor C1, and the patterned layers 26 b, 28II and 26 c forms a second capacitor C2 in accordance with an embodiment. The first capacitor C1 and the second capacitor C2 may have the same or different dimensions. In an embodiment, the first pattern is smaller than the second pattern, and the second pattern is smaller than the third pattern. In some embodiments, the first pattern, the second pattern and the third pattern have similar dimensions.

In an embodiment, the first capacitor C1 includes a MIM capacitor, although other types of materials may be used. In an embodiment, the second capacitor C2 includes a MIM capacitor, although other types of materials may be used. In the embodiment illustrated in FIG. 6, in the first capacitor C1, the bottom electrode extends beyond the lateral boundaries of the top electrode. In the embodiment illustrated in FIG. 6, in the second capacitor C2, the bottom electrode extends beyond the lateral boundaries of the top electrode. In this manner, electrical contact may be made to the bottom electrode from above as discussed in greater detail below. The stacked capacitors C1 and C2 forms the capacitor with dual capacitor dielectric layers 28I and 28II, which can increase capacitance to sustain chips with high performance.

FIG. 6 also illustrates the formation of a capping layer 30 on the capacitors C1 and C2 and the second etch stop layer 24. In an embodiment, the capping layer 30 is formed of a dielectric material such as a silicon-containing material, a nitrogen-containing material, an oxygen-containing material, a carbon-containing material, or the like.

Referring now to FIG. 7, there is shown a second insulating layer 32, a third etch stop layer 34, and a third insulating layer 36 formed over the capping layer 30 in accordance with an embodiment. The second insulating layer 32, the third etch stop layer 34, and the third insulating layer 36 act as a dielectric layer in which metallization layers may be subsequently formed. The second insulating layer 32 and the third insulating layer 36 may include a dielectric or low-k dielectric layer. For example, in an embodiment the second insulating layer 32 and the third insulating layer 36 may include SiO₂, BPSG, TEOS, HDP oxide, SOG, USG, FSG, BLACK DIAMOND™, or other insulating materials. The second insulating layer 32 and the third insulating layer 36 may be formed of a same type of material or a different type of material. The third etch stop layer 34 may be formed of a dielectric material having a high etch selectivity with the material or materials used to form the second insulating layer 32 and the third insulating layer 36. For example, the third etch stop layer 34 may include a nitride such as Si₃N₄, SiC, SiON, TiN, or other dielectric materials.

Next, a second metallization (M2) layer 40 and via plugs 38 interconnecting the first metallization layer 22 with components are formed on the substrate 10 in accordance with an embodiment. As illustrated in FIG. 7, the second metallization layer 40 and via plugs 38 provide an electrical connection to the electrodes of the capacitors C1 and C2. In an embodiment, the via plugs 38 electrically connect the electrodes 26 a, 26 b and 26 c of the stacked capacitors C1 and C2, respectively. Openings corresponding to the second metallization layer 40 and via plugs 38 may be formed in the second insulating layer 32 and the third insulating layer 36 using, for example, a dual damascene process. Conductive material is deposited over the second insulating layer 32 and the third insulating layer 36 to fill the openings. Excess conductive material may be removed using one or more etch processes or CMP processes, leaving the structure shown in FIG. 7. In an embodiment, the conductive material used to form the second metallization layer 40 and via plugs 38 may include, for example, aluminum, copper, tungsten, combinations thereof, or the like. A barrier and/or liner (not shown) may also be used.

Thereafter, other processing steps may be performed, such as, forming additional metallization layers, forming external contacts, thinning a backside of the substrate, attaching one or more dies to the substrate, attaching the substrate to another substrate (e.g., printed circuit board, another interposer, packaging substrate, etc.), and the like.

As can be appreciated, embodiments such as those disclosed herein provide a capacitor integrated on a substrate, such as an interposer, that may avoid issues related to thickness variations that may be caused by an underlying metal feature. For example, by placing the capacitor on the substrate, a more planar surface may be obtained upon which the capacitor may be formed. The metallization layers may be characterized by ridges, and forming the capacitor on these ridges may result in degradation of the voltage breakdown (V_(bd)) and may result in insufficient routing area below the capacitor in high density designs. Embodiments such as those disclosed herein provide a planar surface, e.g., the substrate or a uniform layer formed on the substrate, may remove or reduce these issues. Embodiments such as those disclosed herein provide for a capacitor formed on the substrate and/or between a through via and the metallization layer.

In an embodiment, a method of forming a device is provided. The method includes providing a substrate and forming a capacitor over a surface of the substrate. The capacitor is formed between a lowermost metallization layer and a higher metallization layer.

In another embodiment, a method of forming a device is provided. The method includes forming a through via from a surface of a substrate extending into the substrate; forming a first insulating layer overlying the surface of the substrate; forming a first metallization layer in the first insulating layer, electrically connecting the through via; forming a capacitor overlying the first metallization layer, wherein the capacitor includes a first capacitor dielectric layer over the first metallization layer and a second capacitor dielectric layer over the first capacitor dielectric layer; and forming a second metallization layer overlying and electrically connecting the capacitor.

In yet another embodiment, a device is provided. The device includes a capacitor positioned between a lowermost metallization layer and a higher level metallization layer over a substrate with through vias.

In another embodiment, a device is provided. The device includes a interposer having a through via extending through at least a portion of the interposer, a first metallization layer overlying the interposer and electrically connecting the through via, a second metallization layer overlying and electrically connecting the first metallization layer, and a capacitor positioned between the first metallization layer and the second metallization layer.

Although embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. For example, it will be readily understood by those skilled in the art that many of the features, functions, processes, and materials described herein may be varied while remaining within the scope of the present disclosure. As one of ordinary skill in the art will readily appreciate from the disclosure of the present disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. 

What is claimed is:
 1. A device comprising: an interposer comprising a through via extending through at least a portion of the interposer; a first metallization layer overlying the interposer and electrically connecting the through via; a second metallization layer overlying and electrically connecting the first metallization layer; a first insulating layer formed between the first metallization layer and the second metallization layer; an etch stop layer overlying the first insulating layer; a second insulating layer overlying the etch stop layer, the second metallization layer being partially within the first insulating layer between a lower surface of the etch stop layer and the first metallization layer, and partially within the second insulating layer; a capacitor formed in the first insulating layer positioned between the first metallization layer and the second metallization layer; a first via plug formed in the first insulating layer, wherein the capacitor electrically connects to the second metallization layer through the first via plug; and a second via plug formed in the first insulating layer, wherein the first metallization layer electrically connects to the second metallization layer through the second via plug.
 2. The device of claim 1, wherein the interposer comprises silicon.
 3. The device of claim 1, wherein the through via comprises copper.
 4. The device of claim 1, wherein the capacitor comprises a stack of at least two metal-insulator-metal (MIM) capacitors.
 5. The device of claim 1, wherein the capacitor comprises dual capacitor dielectric layers.
 6. The device of claim 1, further comprising one or more dielectric layers between a bottom electrode of the capacitor and the first metallization layer.
 7. The device of claim 1, wherein the capacitor comprises a planar capacitor.
 8. The device of claim 1, wherein the capacitor comprises a first electrode layer, a second electrode layer, a third electrode layer, a first capacitor dielectric layer between the first electrode layer and the second electrode layer, and a second capacitor dielectric layer between the second electrode layer and the third electrode layer.
 9. The device of claim 8, wherein the first via plug electrically connects to at least one of the first electrode layer, the second electrode layer and the third electrode layer.
 10. The device of claim 1, wherein the first via plug has a consistent width between the second metallization layer and the capacitor.
 11. A device comprising: a substrate comprising a through via extending through the substrate; a first metallization layer overlying the substrate and electrically connecting the through via; a second metallization layer overlying and electrically connecting the first metallization layer; a first insulating layer formed between the first metallization layer and the second metallization layer; an etch stop layer overlying the first insulating layer; a second insulating layer overlying the etch stop layer, the second metallization layer being partially within the first insulating layer between a lower surface of the etch stop layer and the first metallization layer, and partially within the second insulating layer; a capacitor formed in the first insulating layer positioned between the first metallization layer and the second metallization layer, wherein the capacitor comprises a first electrode layer, a second electrode layer, a third electrode layer, a first capacitor dielectric layer between the first electrode layer and the second electrode layer, and a second capacitor dielectric layer between the second electrode layer and the third electrode layer; a first via plug formed in the first insulating layer, wherein the capacitor electrically connects to the second metallization layer through the first via plug; and a second via plug formed in the first insulating layer, wherein the first metallization layer electrically connects to the second metallization layer through the second via plug.
 12. The device of claim 11, wherein the substrate is a silicon interposer.
 13. The device of claim 11, wherein the first, second, and third electrode layers have a material comprising TaN or TiN.
 14. The device of claim 13, wherein the first and second dielectric layers have a material comprising ZrO, HfO, Si₃N₄, or barium strontium titanate (BST).
 15. A device comprising: a substrate comprising a through via extending through at least a portion of the substrate; a first metallization layer overlying the substrate and electrically connecting the through via; a second metallization layer overlying and electrically connecting the first metallization layer; a first etch stop layer over the substrate and the through via; a first electrode layer over the first etch stop layer; a first dielectric structure directly on the first electrode layer; a second electrode layer directly on the first dielectric structure; a second dielectric structure directly on the second electrode layer; a third electrode layer directly on the second dielectric structure; a first insulating layer surrounding and covering the first electrode layer, the first dielectric structure, the second electrode layer, the second dielectric structure, and the third electrode layer on the second dielectric structure; a second etch stop layer overlying the first insulating layer; a second insulating layer overlying the second etch stop layer, the second electrode layer being partially within the first insulating layer between a lower surface of the second etch stop layer and the first electrode layer, and partially within the second insulating layer; a first via plug formed in the first insulating layer, wherein at least one of the first electrode, second electrode, or third electrode electrically connects to the second metallization layer through the first via plug; and a second via plug formed in the first insulating layer, wherein the first metallization layer electrically connects to the second metallization layer through the second via plug.
 16. The device of claim 15, wherein the second electrode layer and the first dielectric structure exposing a portion of the first electrode layer; and the third electrode layer and the second dielectric structure exposing a portion of the second electrode layer.
 17. The device of claim 16, wherein the first via plug extends through the insulation layer and is in contact with the portion of the first electrode layer exposed by the second electrode layer and the first dielectric structure; the second via plug extends through the insulation layer and is in contact with the portion of the second electrode layer exposed by the third electrode layer and the second dielectric structure, and the device further comprises: a third via plug extending through the insulation layer and in contact with the third electrode layer.
 18. The device of claim 17, further comprising: a first conductive member over and in contact with the first via plug and the third via plug; and a second conductive member over and in contact with the second via plug.
 19. The device of claim 15, wherein the first metallization layer is between the substrate and the second etch stop layer.
 20. The device of claim 15, wherein the first, second, and third electrode layers have a material comprising TaN or TiN. 